Analysis of shock tube equilibrium radiation for Earth re-entry applications

This paper presents measurements of equilibrium radiation obtained from the NASA Ames Research Center’s EAST facility and the University of Queensland’s (UQ) X2 facility. Experiments have been conducted in both facilities aimed at measuring the level of radiation encountered during conditions relevant to the Orion lunar return into Earth’s atmosphere. The facilities have targeted the same nominal test conditions, and spectral measurements of the emitted radiance have been obtained across a comparable wavelength range. As this paper is only an overview of the work, as opposed to the full analysis, only preliminary results have been shown with the intention that further comparisons of the spectral intensity across a wavelength range of 300 900 nm will be conducted. At present, a few preliminary results are shown. The methodology behind this paper is to present results from a study that will involve independently reducing the data from raw experimental counts to calibrated radiance in both facilities, and then conducting a comparison between these results. This analysis will endeavor to provide a better understanding of the uncertainty in the measurements, as well as provide a thorough comparison between the X2 and EAST results. Furthermore, this analysis will indicate whether various radiative mechanisms are due to physical processes relevant to flight, or are just facility-dependent phenomena. These phenomena include effects such as contaminating species and the level of the background continuum. Results are shown across a wavelength range of 600-830 nm. NEQAIR simulations will also be conducted for all the EAST and X2 experimental conditions and a comparison conducted. For this overview, a preliminary comparison with NEQAIR has been presented for the nominal test condition.